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Date: Wed, 11 Nov 2020 13:18:32 +0000
From: Marc Zyngier <maz@...nel.org>
To: David Brazdil <dbrazdil@...gle.com>
Cc: kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Dennis Zhou <dennis@...nel.org>,
Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
Mark Rutland <mark.rutland@....com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Quentin Perret <qperret@...gle.com>,
Andrew Scull <ascull@...gle.com>,
Andrew Walbran <qwandor@...gle.com>, kernel-team@...roid.com
Subject: Re: [PATCH v1 15/24] kvm: arm64: Bootstrap PSCI SMC handler in nVHE
EL2
On 2020-11-09 11:32, David Brazdil wrote:
> Add a handler of PSCI SMCs in nVHE hyp code. The handler is initialized
> with the version used by the host's PSCI driver and the function IDs it
> was configured with. If the SMC function ID matches one of the
> configured PSCI calls (for v0.1) or falls into the PSCI function ID
> range (for v0.2+), the SMC is handled by the PSCI handler. For now, all
> SMCs return PSCI_RET_NOT_SUPPORTED.
>
> Signed-off-by: David Brazdil <dbrazdil@...gle.com>
> ---
> arch/arm64/include/asm/kvm_hyp.h | 4 ++
> arch/arm64/kvm/arm.c | 13 ++++
> arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 4 ++
> arch/arm64/kvm/hyp/nvhe/psci.c | 102 +++++++++++++++++++++++++++++
> include/uapi/linux/psci.h | 1 +
> 6 files changed, 125 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm64/kvm/hyp/nvhe/psci.c
>
> diff --git a/arch/arm64/include/asm/kvm_hyp.h
> b/arch/arm64/include/asm/kvm_hyp.h
> index a3289071f3d8..95a2bbbcc7e1 100644
> --- a/arch/arm64/include/asm/kvm_hyp.h
> +++ b/arch/arm64/include/asm/kvm_hyp.h
> @@ -96,6 +96,10 @@ void deactivate_traps_vhe_put(void);
>
> u64 __guest_enter(struct kvm_vcpu *vcpu);
>
> +#ifdef __KVM_NVHE_HYPERVISOR__
> +bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt);
> +#endif
> +
> void __noreturn hyp_panic(void);
> #ifdef __KVM_NVHE_HYPERVISOR__
> void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr,
> u64 par);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 1a57b6025937..28e3bc056225 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -19,6 +19,7 @@
> #include <linux/kvm_irqfd.h>
> #include <linux/irqbypass.h>
> #include <linux/sched/stat.h>
> +#include <linux/psci.h>
> #include <trace/events/kvm.h>
>
> #define CREATE_TRACE_POINTS
> @@ -1498,6 +1499,17 @@ static void init_cpu_logical_map(void)
> CHOOSE_NVHE_SYM(__cpu_logical_map)[cpu] = cpu_logical_map(cpu);
> }
>
> +static void init_psci(void)
nit: init_psci_relay?
> +{
> + extern u32 kvm_nvhe_sym(kvm_host_psci_version);
> + extern u32 kvm_nvhe_sym(kvm_host_psci_function_id)[PSCI_FN_MAX];
> + int i;
> +
> + CHOOSE_NVHE_SYM(kvm_host_psci_version) = psci_driver_version();
> + for (i = 0; i < PSCI_FN_MAX; ++i)
> + CHOOSE_NVHE_SYM(kvm_host_psci_function_id)[i] =
> psci_get_function_id(i);
> +}
> +
> static int init_common_resources(void)
> {
> return kvm_set_ipa_limit();
> @@ -1677,6 +1689,7 @@ static int init_hyp_mode(void)
> }
>
> init_cpu_logical_map();
> + init_psci();
>
> return 0;
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile
> b/arch/arm64/kvm/hyp/nvhe/Makefile
> index c45f440cce51..647b63337a51 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -7,7 +7,7 @@ asflags-y := -D__KVM_NVHE_HYPERVISOR__
> ccflags-y := -D__KVM_NVHE_HYPERVISOR__
>
> obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
> host.o \
> - hyp-main.o percpu.o
> + hyp-main.o percpu.o psci.o
> obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o
> ../entry.o \
> ../fpsimd.o ../hyp-entry.o
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> index 8661bc7deaa9..69f34d4f2773 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -134,6 +134,10 @@ static void handle_host_smc(struct
> kvm_cpu_context *host_ctxt)
> */
> skip_host_instruction();
>
> + /* Try to handle host's PSCI SMCs. */
> + if (kvm_host_psci_handler(host_ctxt))
> + return;
> +
> /* Forward SMC not handled in EL2 to EL3. */
> forward_host_smc(host_ctxt);
> }
> diff --git a/arch/arm64/kvm/hyp/nvhe/psci.c
> b/arch/arm64/kvm/hyp/nvhe/psci.c
> new file mode 100644
> index 000000000000..82d3b2c89658
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/psci.c
nit: can we please name this psci-relay.c, or psci-proxy.c?
We already have a psci.c in the tree, and having the same file name
messes
with my editor... ;-)
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2020 - Google LLC
> + * Author: David Brazdil <dbrazdil@...gle.com>
> + */
> +
> +#include <asm/kvm_asm.h>
> +#include <asm/kvm_hyp.h>
> +#include <asm/kvm_mmu.h>
> +#include <kvm/arm_hypercalls.h>
> +#include <linux/arm-smccc.h>
> +#include <linux/psci.h>
> +#include <kvm/arm_psci.h>
> +#include <uapi/linux/psci.h>
> +
> +/* Config options set by the host. */
> +u32 kvm_host_psci_version = PSCI_VERSION(0, 0);
> +u32 kvm_host_psci_function_id[PSCI_FN_MAX];
> +
> +static u64 get_psci_func_id(struct kvm_cpu_context *host_ctxt)
> +{
> + return host_ctxt->regs.regs[0];
> +}
> +
> +static bool is_psci_0_1_call(u64 func_id)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(kvm_host_psci_function_id); ++i) {
> + if (func_id == kvm_host_psci_function_id[i])
> + return true;
> + }
> + return false;
> +}
> +
> +static bool is_psci_0_2_fn_call(u64 func_id)
> +{
> + u64 base = func_id & ~PSCI_0_2_FN_ID_MASK;
> +
> + return base == PSCI_0_2_FN_BASE || base == PSCI_0_2_FN64_BASE;
I couldn't spot in the spec where PSCI reserves 16bit worth of IDs in
each range.
> +}
> +
> +static bool is_psci_call(u64 func_id)
> +{
> + if (kvm_host_psci_version == PSCI_VERSION(0, 0))
> + return false;
> + else if (kvm_host_psci_version == PSCI_VERSION(0, 1))
> + return is_psci_0_1_call(func_id);
> + else
> + return is_psci_0_2_fn_call(func_id);
Consider using switch/case constructs for readability.
> +}
> +
> +static unsigned long psci_0_1_handler(u64 func_id, struct
> kvm_cpu_context *host_ctxt)
> +{
> + return PSCI_RET_NOT_SUPPORTED;
> +}
> +
> +static unsigned long psci_0_2_handler(u64 func_id, struct
> kvm_cpu_context *host_ctxt)
> +{
> + switch (func_id) {
> + default:
> + return PSCI_RET_NOT_SUPPORTED;
> + }
> +}
> +
> +static unsigned long psci_1_0_handler(u64 func_id, struct
> kvm_cpu_context *host_ctxt)
> +{
> + int ret;
> +
> + ret = psci_0_2_handler(func_id, host_ctxt);
> + if (ret != PSCI_RET_NOT_SUPPORTED)
> + return ret;
> +
> + switch (func_id) {
> + default:
> + return PSCI_RET_NOT_SUPPORTED;
> + }
It would probably help to adopt the same structure as we have in the
KVM PSCI implementation:
switch(psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION:
val = KVM_ARM_PSCI_1_0;
break;
[...]
default:
return kvm_psci_0_2_call(vcpu);
which allows 1.0 to override some 0.2 functions, and otherwise leave
it to the 0.2 backend.
> +}
> +
> +bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt)
> +{
> + u64 func_id = get_psci_func_id(host_ctxt);
> + unsigned long ret;
> +
> + if (!is_psci_call(func_id))
> + return false;
> +
> + if (kvm_host_psci_version == PSCI_VERSION(0, 1))
> + ret = psci_0_1_handler(func_id, host_ctxt);
> + else if (kvm_host_psci_version == PSCI_VERSION(0, 2))
> + ret = psci_0_2_handler(func_id, host_ctxt);
> + else if (PSCI_VERSION_MAJOR(kvm_host_psci_version) >= 1)
> + ret = psci_1_0_handler(func_id, host_ctxt);
> + else
> + ret = PSCI_RET_NOT_SUPPORTED;
Same remark about the use of switch/case.
> +
> + host_ctxt->regs.regs[0] = ret;
> + host_ctxt->regs.regs[1] = 0;
> + host_ctxt->regs.regs[2] = 0;
> + host_ctxt->regs.regs[3] = 0;
> + return true;
> +}
> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
> index 2fcad1dd0b0e..0d52b8dbe8c2 100644
> --- a/include/uapi/linux/psci.h
> +++ b/include/uapi/linux/psci.h
> @@ -29,6 +29,7 @@
> #define PSCI_0_2_FN64_BASE \
> (PSCI_0_2_FN_BASE + PSCI_0_2_64BIT)
> #define PSCI_0_2_FN64(n) (PSCI_0_2_FN64_BASE + (n))
> +#define PSCI_0_2_FN_ID_MASK 0xffff
>
> #define PSCI_0_2_FN_PSCI_VERSION PSCI_0_2_FN(0)
> #define PSCI_0_2_FN_CPU_SUSPEND PSCI_0_2_FN(1)
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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